Powered air purifying respirator system and breathing apparatus

ABSTRACT

A combination of an SCBA system for providing bottled air to a user and a PAPR system for purifying ambient air for use by a user wherein the two systems are used alternatingly depending on the contaminated condition of the ambient air and the oxygen content of the ambient air.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/393,346, filed Mar. 21, 2003, entitled “Towered Air PurifyingRespirator System and Breathing Apparatus.”

FIELD OF TECHNOLOGY

This invention is directed to an apparatus for assisting persons tobreathe in hostile environments. It more particularly relates to such anapparatus that is useful in purifying contaminated air as well asproviding portable clean air.

BACKGROUND

There are, at present two systems for assisting the breathing of personswho are subject to contaminated air. First, there are the poweredrespirators (SCBA-Self Contained Breathing Apparatus) that feedcompressed (e.g. bottled) air to a tight fitting face mask, or otherconduit to the mouth and/or nose, for inhaling by the user. Thesesystems do not permit the user access to the ambient atmosphere at all.Second, there are filter/decontamination systems for use in the form ofa canister, in connection with a respirator apparatus that rely oncleaning ambient atmosphere to make it suitable for breathing. Suchfilter systems may or may not make use of auxiliary power. In poweredsystems, ambient atmosphere is drawn through a suitablefilter/decontamination means, or other purifying means, by a powered fanor the like, such that the contaminated ambient air is renderedbreathable. The purified resultant air is fed to a headpiece-of-somekind, such as a tight fitting facemask (the complete system is known asa Powered Air Purifying Respirator (PAPR)). Both types of breathingassists are used by personnel who are subject to breathing ambientatmosphere that would otherwise be considered to be harmfullycontaminated, unbreathable or dangerous.

A dangerous or unbreathable atmosphere is considered to be aircontaining less than 19.5 volume percent oxygen, or air with therequisite oxygen, but also containing significant proportions of harmfulcontaminants, e.g. particulate or gaseous, is considered contaminatedand harmful. It will be appreciated that, in some situations, (where theoxygen content is at least 19.5%), the wearer may be able to enter anarea that has a contaminated atmosphere using only a filter systemprovided the filter(s) is capable of meeting the challenge of thecontamination whereby cleaning the atmosphere and enabling the user tobreath and still preserve his health. The filter can be provided withmeans to eliminate harmful constituents in the wearer's ambientatmosphere. In particular, filter based decontamination systems, that isthose systems that purify an ambient atmosphere that has becomecontaminated so as to convert it to breathable air, work best when theypass an air supply under positive pressure through a cleaning element(such as a suitable filter). That is, a pump/fan is used to draw thecontaminated atmosphere through a filter, and perhaps into contact witha material that ameliorates the contaminant(s), and to then force thepurified, e.g. filtered, air under positive pressure into a face mask orother means associated with the breathing of the wearer, such as a mouthgrip, hood or helmet. While a powered air supplying means, such as abattery operated pump/fan means, is probably preferred, it is also knownthat air cleaning systems that are not powered by external means can beused. In these unpowered systems, the user's lung power provides thenecessary impetus to force contaminated air through the cleaning elementand feed it to the user. For simplicity, this means of cleaning ambientatmosphere will be referred to as an Air Purifying Respirator (APR).When the air is forced through the system due to the use of a battery,line current or other powered pump or fan arrangement, these operatingsystems are known as a Powered Air Purifying Respirator (PAPR)

A powered air purifying respirator system (PAPR) will protect againstcontaminants so long as the oxygen level in the purified air is above19.5 volume percent and provided the contaminants are such as can beremoved by filtration, e.g. soot and smoke, and/or can be ameliorated byreaction with a suitable purifying material. In practical effect, thesesystems have been designed to use replaceable filter(s) and airpurifying canister(s). However, they are of no value where the ambientatmosphere has an oxygen content that is less than 19.5% by volume.

Other situations exist, such as high heat load, where the ambientatmosphere is so contaminated, or the contamination is such, that afilter and/or decontamination/purifier system cannot handle the problem;and/or the oxygen content of the ambient air is too low to satisfy humansurvival needs or has a high toxic concentration or high temperature(that is, where the atmosphere is IDLH, that means the ambientatmosphere is of Immediate Danger to Life and Health). In thosecircumstances, a person entering the area with such level and type ofcontamination must take his own air supply along with him. This is akinto a SCUBA diver carrying his air with him in the form of a container(bottle) with compressed, clean air in it.

One problem is that a wearer of a SCBA must support all of the weight ofthe bottled air whereas, in water, a diver has the advantage of thewater's buoyancy to help support the weight of the SCUBA tanks. Even so,most SCBA systems are only capable of carrying enough bottled,compressed air for up to about an hour's use. It would, of course, bemost desirable to be able to increase the time that a user, for examplea fire fighter, can work in a hostile environment dependent upon bottledair while at the same time minimizing the weight that the person mustcarry to support him for that additional time.

It will be appreciated that air bottles are heavy, especially when theyare full. In the case of fire fighters, they are already going into anunfriendly environment carrying their tools with them, and the heat ofthe fire makes it even more difficult to carry the extra weight of thecompressed air container. Further, the fire fighter must often proceed,from the safe ambient air outside the area where a fire has merelycontaminated the atmosphere to an extent such that it can be cleaned, bywearing some form of APR, for a relatively long distance before hereaches an area where the contamination is of such an extent that theatmosphere cannot be reasonably cleaned and where he must breath the airhe brought with him, or strangle from lack of oxygen, or be harmed byother contaminants.

When carrying around ones' own air supply, there is a very realpractical limit as to how much air can be safely carried. Contrary tooperating under water with a SCUBA rig, the air bottles used by firefighters are quite heavy, must be supported entirely by the wearer, anddo not have the advantage of water buoyancy partially supporting theirweight. Making them larger, to be able to carry more air, increasestheir weight but decreases their portability. This combination of weightand working conditions severely limits the time that a fire fighter, whois wearing/carrying his own air supply and tools, can effectively fightthe fire.

Thus, there exists a situation in which a fire fighter, for example,does not need carried air for some portion of the time that he isworking on the fire, but does need portable, bottled air for otherportions of the time that he is working on the fire. Yet, existingsystems are suited to one or the other; that is, the existing systemseither provide positive pressure (pumped) filtering and purificationsystems to convert contaminated ambient atmosphere to air that is cleanenough to breath safely, or they provide bottled air under pressure thatis carried by the person to be used instead of the ambient atmosphere.While both systems have deficiencies, each system has advantages, evennecessities, under critical conditions.

The above and following comments use a fire fighter as illustrative ofthe type of person who will benefit from using the instant invention.However, this invention is by no means limited in use to fire fighters.Workers in chemical plants and refineries will have substantial need forthe benefits available from the instant invented system. Soldiers in thefield that are being subjected to chemical or biological attack willbenefit greatly from the instant system. It will be apparent to those ofordinary skill in this art that others will similarly be assisted by theinstant invention.

SUMMARY

It is therefore an object of this invention to provide a hybrid assistedbreathing apparatus that has the advantages of both the SCBA and thePAPR systems.

Other and additional objects of this invention will become apparent froma consideration of this entire specification.

In accord with and fulfilling this object, one aspect of this inventionis a breathing assisting apparatus comprising a tight fitting face mask,or other conventional means of bringing respirating air to a person inneed thereof, that is adapted to be tightly fitted to a person's face ormouth or nose (or any combination thereof). For ease of understanding,further reference will be made to the use of a face mask. However, thisuse is illustrative and not limiting. A mouth piece can also serve thefunction of bringing the breathable air to the user.

Under complete manual operation, the PAPR and SCBA are each connected tothe face mask by its own breathing hose, each with its own entry point,in the case of a dual entry face mask, or, via a “tee” piece, or similarconnection device in the case of a single entry face mask. At or aboutthe face mask each is provided with a non-return (one way) valve. Anexhaust valve is provided in the face mask so that exhaust air is ventedto the atmosphere. A valving and/or switching system is provided so thatthe wearer controls whether to receive cleaned ambient air or supplied(bottled) air. This valving and/or switching system can be manuallyoperated by the user, in which case the user determines, independently,which air supply to use; or it can operate under semi-automatic controlvia sensors where the air supply from the SCBA and the PAPR are bothconnected to the mask or connected to a valve manifold. On start up, theSCBA supply is in a shut off condition and the PAPR is in an oncondition. Air is passed to the face mask via the PAPR. Either at thediscretion of the wearer or in response to an audible and/or visualalarm which operates based on sampling and testing the ambient air andindicates by way of the alarm that the system should be switched fromPAPR to SCBA operation, the wearer opens the SCBA supply valve and thenswitches off the PAPR. The pressure of the SCBA air, on exhaust, willoperate valves automatically switching off the PAPR leaving the airsupply solely on SCBA. In the alternative, the decision as to whether toaccept purified air from the canister/filter assembly, or to demand airfrom the supplied air bottle means; can operate automatically based onsampling and testing means associated with the valving means which wouldbe electrically operated so as to open access to the SCBA and closeaccess to the PAPR via the manifold valves.

At least one air bottle is provided with a connection to at least oneport in the face mask and a controllable valve is provided that permitscontrol as to whether to withdraw air from the bottle(s) or not. Atleast one filter or canister is provided, separate from the airbottle(s), also with a controllable valve system that permits control asto whether ambient air is taken in by the PAPR and fed to the mask. Abattery or other powered electric motor driven fan, that is operativelyattached between the filter or canister and to the user, is providedwith means, such as a switch or a handle, to enable the motor driven fanto be operated or not.

Thus, when the ambient air has sufficient oxygen content, and thecontaminants are suited to removal by filtration or treatment in thecanister, the fan can be activated by operating the switch and ambientair will be powered through the filter or canister where it is purifiedof its harmful constituents, such as soot and other harmful particles,vapors or gases. Under manual operation when the ambient air hasinsufficient oxygen, or the contaminants are such that they cannot beremoved by filtration or other treatment in the filter(s) orcanister(s), the valve of the SCBA is opened by the wearer, and the PAPRis switched off. Ambient air is no longer taken in through thefilter(s)/canister(s). Instead, it is now being supplied by the SCBA.

Where a face mask is used, it is suitably equipped with a one way valvethat enables exhausted, exhaled air to be vented regardless whether theintake air was derived through the filter canister or from the bottledcompressed air. It is considered to be within the scope of thisinvention for it to be used in conjunction with a closed circuitapparatus.

As is conventional, the bottled air, that is under substantial pressure,must have its pressure reduced to an extent sufficient to enable it tobe breathed by the user without damage to their respiratory system. Thisprocedure, and equipment to enable this to be accomplished, is wellknown per se. Suitably, commercially available first and second stageregulators can be used for this purpose. Thus, there are in effect twosuccessive valving systems disposed between the air bottle and the facemask: a first valve that is a simple open or close valve that isattached at or very near the air bottle; and a regulator, pressurereducing valving system that is disposed in the line between the firstvalve and the face mask.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of an apparatus according to thisinvention with parts omitted for ease of understanding;

FIG. 2 is a perspective view of one aspect of the apparatus according tothis invention in a fully assembled condition; where the PAPR and, theSCBA both use a common hose to connect to the face mask;

FIG. 3 is a schematic diagram of a first embodiment of an air supplysystem according to this invention;

FIG. 4 is a schematic diagram of a second embodiment of an air supplysystem according to this invention;

FIG. 5 is a schematic diagram of a third embodiment of an air supplysystem according to this invention; and

FIG. 6 is a schematic diagram of a fourth embodiment of an air supplysystem according to this invention; and

FIG. 7 is a schematic diagram of the fourth embodiment of the inventionwith some modifications.

DETAILED DESCRIPTION

Referring now to the drawing, there is shown in FIGS. 1 and 2 anapparatus that comprises a face mask 10 that is adapted to be tightlyfitted to the face of the wearer against incursion by the ambientatmosphere (for clarity, the user is not shown wearing the mask. Furtherfor clarity, the alternative mouth and/or nose breathing elements arenot shown). A hose 14 connects the face mask 10 directly to source ofbreathable air, such as air that has been cleaned and is forced into theface mask by means of a blower motor and fan assembly 15 (see FIGS. 1, 2and 6). In this embodiment, the face mask 10 is also connected directlyto a compressed air bottle 22 via a hose 27. Note that in thisembodiment, the face mask itself is the plenum chamber into whichbottled air as well as cleaned ambient air are both forced.

The blower motor and fan assembly 15, is operatively connected to aplenum chamber assembly 18 has attached to it a plurality of filterelements 16. Engaging the impeller fan 25 is adapted to cause ambientair to be drawn through the filters or canisters (containing suitabledecontamination 16 where it is to be cleaned of solid particulatematter, harmful gases and/or odors to produce cleaned air 19. Subject tothe class of canisters fitted and the time spent in the contaminatedarea, the canisters may provide breathable air in a chemically,biologically or nuclear contaminated environment.

The cleaned air, which presumably has sufficient oxygen content, whichis adapted to be drawn by the fan 25 into operative relationship withthe face mask 10 and thereby provide breathable air to the wearer. Thecleaned air 19 can be fed directly to the mask 10, as shown in FIG. 6,or it can be deployed to the face mask 10 through a second plenumchamber 21 as shown in FIGS. 3, 4 and 5.

Thus, one embodiment of this invention separates the source of cleanedambient air from the source of bottled air (suitably supplied from anormal atmosphere) by providing separate access 30 and 32 to the facemask 10. Each of these separate entry points is suitably adapted to beclosed by a valve 34 and 36 which are one way or no return valves. Thatis, these valves 30 and 32 and the air pressure from the source of airsupply for the time being, permit air to flow into the face mask 10 butdo not permit the air contents of the face mask to flow out of the facemask back into the alternative source of air supply and purificationsystem. There is also provided a separate valve 38 that is also a oneway valve that allows the contents of the face mask 10 to vent from theface mask 10 to ambient atmosphere. This venting valve 38 is so designedthat it only opens when the gaseous contents of the facemask 10 are at apressure greater than ambient.

In other embodiments of this invention, the face mask 10 is connected toa plenum chamber 21 via a hose 14 a. The plenum chamber 21 is adapted tobe fed from the air bottle 22 through a hose 27 via a regulator 12 and ashut off valve 24. The plenum chamber 21 is also adapted to be fedpurified air 19 from the filters/decontamination canisters 16 throughthe fan 25 via hose 29. The plenum chamber 21 can be fed with bottledair or purified air in the alternative.

In FIGS. 3, 4 and 5 the face mask 10 is shown to be connected, via ahose 14 a, to a plenum 21 which in turn, is connected to both acompressed air bottle 22 via a hose 27. The plenum 21 is also connected,via a hose 29 through the blower impeller 25, to the plenum chamber 18,thence to filters/decontamination canisters 16 and on to an ambient airintake 31. The air bottle 22 is connected to the plenum 21 via a hose27, a regulator 12 and a shut off valve 24. The plenum chamber 21 hassuitable valve means 34 and 36 that is adapted to control the flow ofair from either the air bottle 22 or the filter/decontaminationcanisters 16. The impeller fan 25 provides means for moving ambient airthrough the intake 31 and through the filter/decontamination canistersinto the face mask.

The filter/canister plenum chamber 18 supports at least one, andpreferably a plurality of filters or canisters 16. The exit 19 from eachcanister is preferably operatively associated with the openings 21 inthe mask plenum 21 so that contaminated air drawn into eachfilter/decontamination canister 16 by means of the motor driven fan 25is cleaned and then powered by the fan 25 into the face mask 10 via thehose 14 a and the regulator valving system 21.

In FIGS. 1 and 2 here are shown three (3) canisters 16 each of whichcontain filter medium. One or more of the canisters can also containsuitable materials that serve to decontaminate the ambient environmentalair by eliminating harmful components that are not filterable.

The canisters can be assembled, in a preferred embodiment, so that eachcanister has a separate intake opening 20 and a separate exit 19. Allair passing through any and all specific filter/decontaminationcanister(s) exit into a manifold plenum 18, having an air collectionchamber 33 that is operatively associated with the fan means 25 asstated above. The individual filter/decontamination canisters can beused individually or in plural configuration and may be fitted all onone side of the filter plenum chamber 18 or fitted some one side andsome the other to the desired quantity.

A lever handle or rotary handle 43 is connected to filter cover(s) 44and the motor on/off switch 45. In the semi-automatic or automatic modethe lever 43 can be solenoid operated. In the motor-off position, thefilter cover(s) is disposed over the air entry port(s) of thefilter/decontamination canister(s) thereby preventing any air fromentering the filter/decontamination canister(s). This function providesthat while the apparatus is operating in a SCBA mode in a contaminatedatmosphere, the filter/decontamination canisters are not taking in anycontaminated air and therefore are not becoming unnecessarilycontaminated. By being linked to the on/off switch, this ensures thatthe filter/decontamination canister(s) airways are open when the PAPR isswitched on.

The air cylinder 22 is assembled into a conventional harness 17 andoperatively associated with the PAPR manifold plenum chamber 21 suchthat air released from the air cylinder bypasses the filter media in thecanisters and proceeds directly to the plenum chamber 21 and thencethrough the hose 14 a into the face mask 10. A gas pressure regulator 12is required for use with the bottled air in order to let the bottlepressure down to a pressure that is manageable by the user.

It should be noted that the plenum 21 can be operated in any of threemodes. Under manual control, starting in PAPR mode, the PAPR would beon, the main cylinder 22 valve would be open, the second stage regulator12 would be closed, the valve 34 in the plenum 21 would be closed andvalve 36 would be open due to the pressure of air from the blower motorassembly 15. When the wearer determines that the atmosphere is in dangerof becoming un-breathable or contaminated by a challenge greater thanthat the filter canisters being worn, are designed to take, the wearerwill open the second stage regulator 12, the resultant air pressure willopen valve 34 and air will pass into the plenum 21. The resultantpressure in the plenum 21 will close the valve 36 shutting off air fromthe PAPR. The wearer will now be breathing only bottled air. The wearerwill switch off the power supply to the PAPR blower motor 15.

In semi-automatic or automatic mode, starting in PAPR mode, the PAPRwould be on, the main cylinder 22 valve would be open, the second stageregulator 12 would be closed, the valve 34 in the plenum 21 would beclosed and valve 36 would be open due to the pressure of air from theblower motor assembly 15. When by means of sensors it is determined thatthe atmosphere is in danger of becoming un-breathable or contaminated bya challenge greater than that the filter canisters being worn, aredesigned to take, the system will sound an audible alarm which instructsthe wearer to open the second stage regulator 12, the resultant airpressure will open valve 34 and air will pass into the plenum 21 or, thesystem will automatically open valve 34, valve 36 would close and thePAPR switched off.

In fully automatic mode, starting in PAPR mode the PAPR would be on, themain cylinder 22 valve would be open, the second stage regulator 12would be open, the valve 34 would be held closed electrically, orelectro-mechanically, in the plenum 21 and valve 36 would be open due tothe pressure of air from the blower motor assembly 15. When by means ofsensors it is determined that the atmosphere is in danger of becomingun-breathable or contaminated by a challenge greater than that thefilter canisters being worn, are designed to take, the system willswitch the control to valve 34 which would then open, and air will passinto the plenum 21 closing valve 36 and then the PAPR would be switchedoff.

1. In a breathing apparatus of the type having a facemask, a source ofbreathable gas under pressure, a first conduit operatively leading fromsaid source of breathable gas, a filter system comprising a filterand/or a decontamination medium, a second conduit operatively leadingfrom said filter system, a blower adapted to move air under positivepressure through said filter system and into said second conduit, athird conduit operatively connecting said first and second conduits tosaid facemask, at least one valve operatively associated with said firstand second conduits, adapted to control the flow of air from said filtersystem and pressurized gas from said source of breathable gas, such thatbreathable air is supplied to a user; wherein the improvement comprises:a sensor adapted to determine whether air emerging from said filtersystem is safely breathable; and a signal generator operativelyassociated with said sensor, adapted to generate a signal indicative ofwhether said air emerging from said filter system is safely breathable.2. The breathing apparatus as in claim 1, further comprising acontroller to open and/or close said valve in response to said signal.3. The breathing apparatus as in claim 2 wherein said opening or closingof said valve is in automatic response to said signal.
 4. The breathingapparatus as in claim 2 wherein said valve is adapted to substantiallyimmediately completely close off said second conduit when said signalidentifies the ambient air as being of Immediate Danger to Life andHealth (IDLH).
 5. The breathing apparatus as in claim 1 wherein saidsignal is detectable by said user, and further comprising an operatorfor opening or closing said valve that is operable manually by saiduser.
 6. The breathing apparatus as in claim 1 wherein said sensor isadapted to determine if the composition of gas emerging from said filtersystem comprises a sufficient amount of oxygen to be safely breathable.7. The breathing apparatus as in claim 1 wherein said sensor is adaptedto determine if the composition of gas emerging from said filter systemcomprises a sufficiently small amount of particulate matter to be safelybreathable.
 8. The breathing apparatus as in claim 1, further comprisinga regulator operatively associated with said source of breathable gasunder pressure to enable delivery of said pressurized breathable gas tosaid user of said apparatus.
 9. The breathing apparatus as in claim 1wherein said filter system is sufficient to trap solid particles inambient air and/or to enable ambient air in need of cleaning to have aresidence time in contact with said decontamination medium that issufficient to decontaminate contaminating vapors and gases in saidambient air to form cleaned air that is safe to inhale.
 10. Thebreathing apparatus as in claim 1 wherein said fan and motor assemblymoves said ambient air from external of said apparatus into operativerelationship with said filter/decontamination medium.
 11. The breathingapparatus as in claim 1 wherein said fan and motor assembly iselectrically powered.
 12. The breathing apparatus as in claim 1 furthercomprising a plurality of filter/decontamination media.
 13. Thebreathing apparatus as in claim 1 wherein said facemask is adapted toestablish and maintain a seal with the face of said user so as toisolate at least the nose and mouth of said user from ambient air, andadapted to maintain said seal under conditions of positive pressurewithin said facemask.
 14. The breathing apparatus as in claim 1 whereinsaid first conduit is disposed in operative relationship to and betweensaid source of breathable gas and said facemask, said second conduit isdisposed between said filter system and said facemask, and said valve isadapted to control the flow of cleaned air from said filter systemand/or pressurized breathable gas to said facemask.
 15. The breathingapparatus as in claim 1, further comprising a plenum chamber operativelyassociated with said first and second conduits such that cleaned airfrom said filter system and pressurized gas from said source ofbreathable gas, respectively, are adapted to flow into said plenumchamber and said third conduit is disposed between said plenum chamberand said facemask.
 16. The breathing apparatus as in claim 1, furthercomprising at least one one-way exhaust valve operatively associatedwith said facemask and operative when said user exhales wherebyincreasing the internal pressure in said facemask above the pressureimposed by said powered forcing of ambient air, and above the pressureimposed by gas being fed from said source of breathable gas.
 17. Thebreathing apparatus as in claim 1 wherein said gas in said source ofbreathable gas comprises air.
 18. The breathing apparatus as in claim 1wherein said pressurized gas comprises oxygen admixed with asubstantially inert gas.
 19. The breathing apparatus as in claim 1wherein said source of breathable gas comprises a plurality ofcontainers adapted to contain gas under pressure.